Loud-speaker



vJune 17, 1930. F, R, BECKERT- 1,765,257

LOUD SPEAKER Filed sept. 15, 1924 I-ILs Attorrjgy Patented Junel 17, 1930 UNITED STATES PATENT.. ori-fica* FRANK R. BECKER-T,

LOUD-SPEAKER In the most common type of such devices, a.

iiat' diaphragm rigidly supported at its periphery has been employed and this has been actuated by forces applied near, the. center. Such a diaphragm when actuated in this way may have several different natural periods of vibration within the range of frequencies i of the sounds to be reproduced. Consequently, any sounds which hap en to be ofthe same vfrequency as any one of t ese natural periods will be reproduced in greater relative volume l than. sounds having other 'frequencies yI overcome this disadvantage to 'a large e'X- tent by'applying the actuating orceto the diaphragm at a plurality of points uniformly distributed over its area and provide means for applying .substantially equal actuating forces at the different points of application.

By this provision, the greater part of the `diaphragm is caused to move as a whole and substantially all of the internal stresses produced take place near its periphery. A dia phragm constructed and operated in this way will'not have the pronounced natural periods characteristic of theusual diaphragnis, and

such natural periods as it may have may be made to be greatr than the frequency of' any la5 of the ordinary sounds which are to be reproduced.

The novel features which I believeto be characteristic of my invention are set forth with particularity in the appended claims.

My invention'itself, however, both as to its organization and method of operation will best be understood by reference to the followingl description taken in connection with the accompanying drawing in which Fig. 1 is a vertical section of a device embodying my invention; Fig. 2 is another vertical section taken along the line 1--1 of Fig. 1; and Fig. 3 is a horizontal section taken alongthe line 2-2 of Fig. 2. l

60 As indicated in the drawings, a base 1 is provided having attached thereto an upright supporting member 2. The actuating mecha- OF SCHENECTADIZ, NEW YORK,` SIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK msm comprises a pair of permanent magnets 3 and 4 each of whichhas opposing 'poles 5, 5 separated by a short air gap. The magnets are held in proper spaced relation to each other by a bridging member 6 towhich they may be secured in any desired 'mannen The bridging member is secured by means of screws "7 to the bracket 8 which in turn is secured to the supporting'member 2 by means of screws 9 and is vertically adjustable with respect thereto by means of screws 10.

A diaphragm actuating element or-armature 11 is mounted in the air gaps of magnets 3 and 4 and between the two magnets is sur.- rounded by actuating coils 12. These actuating coils are secured. to a bracketl which in turn is secured to the support 2. A rigid diaphragm 14 is clamped between two rings 15 and 16. The lower' ring 15 is supported from the base 1 by means of the supporting member 2 and a rod 17. The upper ring 16 is provided with a central opening 18 surrounded by a tube over which the horn 19 may be fitted. The actuating elementll is secured to the diaphragm 14 by means of four rods or struts 20, these rodsv being fastened by means of nuts, as indicated in the drawing, to four points uniformly distributed over the area of'l the diaphragm. The actuating element 11 is symmetrically disposed in the air gaps of the magnets so that when actuating currents are supplied to the4 coils 12 all parts of the element located in` the air gaps: will have substantially the same movement relative to the magnet poles and substantially equal driving forces will be applied at each of the four points on the diaphragmv to which the rods 20 are attached. l l' The actuating element and diaphragm together form a rigid structureand substantially all of thevarea of the diaphragm enclosed within the points to which the driving forces are applied moves as a Whole. The only internal stresses produced in the diaphragm will be near the periphery and if the diaphragm has any natural periods they will in most cases be above the normal sound fre quencies.

\ cases be improved by the addition of a dia-l The operation of the device maylin some phragm damping device.` Thismay comprise a spring) member2l which vis secured to the -ring l5 y means of screws-22 and which .car-

ries at 'its free end a pad 23 of felt or other resilient material. Thepress'ure of this pad- 23 against the diaphragmumay be adjusted by means of a set screw 24,- the end of which bears against spring member 2 1.

While I have shown and described only one embodiment of my invention, it is apparent that many modifications may be made in the structures used in carrying it intoeifect Without .departing from" the scope thereof as set said diaphragm.` 2.' A sound reproducing device comprising.

' Y'a diaphragm,

forth in thev appended claims.

" What I claim as new and desire to secure by Letters Patent of the United States, is,-' l. A sound reproducing device comprising ,.20 a diaphragm, a magnet having a pair of opposing poles separated byl a short air gap and an armature located in said airv gap and spaced from said diaphragm, said. armature being supported from a pluralityvoffpoints on means for vibrating said diav phragm, said means including a magnet, said magnet comprising an armature supported at v a plurality of points on said diaphragm, and `a .pair of pol'epieces cooperating with opposite sides of said armature, said armature l se l va diaphragm, a magnet being adapted to exert a driving force on said diaphragm. f f

3. "A sound reproducing device comprising having a pair of op- I posing polesseparated by a shortair gap, an

armature located in said air gap and support# 'ed from al plurality of points on said dia- Ifsad armature.

4.. A sound reproducing device comprising a pai of magnets each of which .has a. pair o opposingpoles separated by a. short -air gap, and an armature located in l .the air gaps and between the opposing poles s' of said magnets said armature being vsupported from a plurality of points on said diaphragm. Y

a diaphragrmia pair of magnets each of which has a pair of short air gap, and an armature located in the air gaps and between the opposing polesof said magnets, said armature being adapted to exert substantially equal driving forces on said diaphragm at a plurality of different 6.1A sound reproducing device comprising a diaphragm, a pair of magnets each of which v hasa pair of opposing poles separated by a short air gap, and an armaturelocated in the airgaps of said magnets and supported from a plurality of points on said diaphragm, said armature being so constructed and arranged ing a diaphragm,

v"'ffidapted to exert su phragm, and an actuating coil surrounding 5. A' soundreproducing device comprising l opposing poles separated vby'a that when actuated'all parts thereof in the air gaps will have substantially the same relative movement with respect to the magnet poles.

7 A sound reproducing device com rising a diaphragm andan armature adapte .to actuate said diaphragm, said armature being spaced from but rigidly connected at -a plu-y rality of points to a plurality of corresponding points on said diaphragm.

8." A sound reproducing device comprising a diaphragm and an armature adapted to actuate said diaphragm, said armature being spaced from but rigidly connected at a plurality of pointstoaplurality of correspondm, vsaid armature'vv comrigidly connected at a plurality of points to a plurality of corresponding-points on said diaphragm, and actuating means forl said armatureso'arran ed ,that the armature is stantially equal driving orces on said diaphragm at all of the points uofconnections thereto.

1l. An electromagnetic sound reproducer ing points uniformly distributed over the` Vreproducing device'comprising y and an armature adapted to .er 'arranged in a lanearallelto the plane of sai l dia.-

' comprising a single member spaced from -but comprising in .combination a casing, permanent magnetic means, electromagnetic means located between said permanent magnetic means, afreely floating armature' positioned within both of said means, a diaphragm in said casing and a connection between opposite ends of said freely floating armature and said diaphragm whereby vibrations transverse to the axis of said electromagnetic means may be imparted to said diaphragm.

`In witness. whereof, I have hereunto set my hand this 13th day of September, 1924.

FRANK R. BECKERT. Y 

